Transcript
Interquartile Range
Conceptual Explanation
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
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Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
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25th
percentile
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
50th
percentile
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25th
percentile
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
50th
percentile
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25th
percentile
This is called the MEDIAN
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
50th
percentile
1 2 3 4 5 6 7 8 9
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5
25th
percentile75th
percentile
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
50th
percentile
1 2 3 4 5 6 7 8 9
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3
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5
25th
percentile75th
percentile
This means that 25% of the scores fall below this point.
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
50th
percentile
1 2 3 4 5 6 7 8 9
1
2
3
4
5
25th
percentile75th
percentile
This means that 25% of the scores fall below this point.
This means that 75% of the scores fall below this point.
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
1 2 3 4 5 6 7 8 9
1
2
3
4
5
25th
percentile75th
percentile
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
1 2 3 4 5 6 7 8 9
1
2
3
4
5
25th
percentile75th
percentile
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
1 2 3 4 5 6 7 8 9
1
2
3
4
5
25th
percentile75th
percentile
50% of the scores fall between these two
points
Interquartile Range
Interquartile Range
The interquartile range represents the distance between the 25th percentile and 75th percentile.
1 2 3 4 5 6 7 8 9
1
2
3
4
5
25th
percentile75th
percentile
50% of the scores fall between these two
points
This is the Interquartile Range!
Interquartile Range
Purposes of the Interquartile Range (IQR)
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
9t 8t 7t
7t
5t
6t
6t
5t 4t
6t
5t
5t
3d 2d 1st
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3d4t
4t
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
9t 8t 7t
7t
5t
6t
6t
5t 4t
6t
5t
5t
3d 2d 1st
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3d4t
4t First
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
9t 8t 7t
7t
5t
6t
6t
5t 4t
6t
5t
5t
3d 2d 1st
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3d4t
4t FirstLast
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
2. Highly Skewed Data
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
2. Highly Skewed Data
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5 6
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5 7
7 22 23
1 2 3 4 5 6 7 23
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22
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
2. Highly Skewed Data
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5 6
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5 7
7 22 23
1 2 3 4 5 6 7 23
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22
Mean = 7Median = 5
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
2. Highly Skewed Data
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5 6
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5 7
7 22 23
1 2 3 4 5 6 7 23
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22
IQR
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
2. Highly Skewed Data
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5 6
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5 7
7 22 23
1 2 3 4 5 6 7 23
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IQR Standard Deviation = 5.3
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
2. Highly Skewed Data
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IQR
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Standard Deviation = 2.3
Notice how the Standard Deviation drops from
5.3 to 2.3.
Interquartile Range
Purposes of the Interquartile Range (IQR)
The Interquartile Range (IQR) is a helpful measure of spread for two scenarios.
1. Rank ordered Data
2. Highly Skewed Data
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3
5
4
4
5 6
4
5
5 7
7 8 9
1 2 3 4 5 6 7
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IQR
8 9
Standard Deviation = 2.3
Notice how the Standard Deviation drops from
5.3 to 2.3. However the IQR stays
the same.
Interquartile Range
The EndInterquartile Range
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